An ideal amplifier provides a constant gain and offset over a wide range of temperatures without the need for feedback control. However, for a real amplifier, the gain and offset vary due to changes in temperature and linearity effects. For example, as operating temperature increases, gain tends to decrease. To overcome temperature effects, the gain and offset of the amplifier is actively compensated.
Gain variations due to temperature changes can be actively compensated using a closed loop feedback circuit. The output power is compared to a reference and any deviation of the output power from the reference power causes a control circuit to adjust the amplifier's gain. This automatic gain compensation technique works as long as the amplifier's behavior across a temperature gradient can be determined or predicted. However, such circuits are difficult to mass produce reliably and often require manual trimming to account for deviations among the closed loop components and the out of loop temperature effects.
Similarly, temperature dependent resistive networks or a closed loop feedback circuit can be used to compensate for offset variation due to temperature or other operating conditions. However, these circuits usually require manually setting the offset initially and are limited by the accuracy of the analog components.